The advancement of television technique has reached a level of implementing a device for displaying a stereoscopic image. Various stereoscopic image display schemes have been proposed, and at a time when the present invention is filed, a full-fledged commercialization of a stereoscopic type 3D television is at hand. In a stereoscopic 3D system, two images are captured by using two image sensors which are away from each other by about 65 millimeters, just like the human's eyes, and the captured images are transmitted as a broadcast signal to a receiver. Then, the receiver makes the two images separately inputted to left and right eyes of a viewer (i.e., a user), thereby simulating binocular disparity to allow for a depth perception and stereoscopic vision.
In the stereoscopic display device, two images, namely, left and right images, constituting a pair of stereoscopic images are accurately inputted to the left and right eyes of the viewer. That is, it is important to prevent the two images from being simultaneously inputted to any of the two eyes not to cause interference. In order to exclude interference, the existing stereoscopic display device may require special glasses such as shutter glasses controlling the passage of left and right images in a time division scheme, anaglyph glasses using a spectrum difference, polarization glasses using polarization, and the like. Among them, the shutter glasses are configured such that only a left-eye shutter of the shutter glasses is open when a left image is displayed on a display screen of a display device, and only a right-eye shutter is open when a right image is displayed, in order to deliver the left and right images to a viewe's left and right eyes, respectively.
However, the related art have fixed light transmission characteristics, for example, brightness and color temperature, so it cannot properly reflect a viewer preference or image characteristics. Namely, the viewer may desire to view a brighter or darker image or adjust color temperature because of his preference or surrounding environments or in consideration of types of images, but the existing glasses fails to satisfy these needs.